Cardiovascular System, Blood Vessels: Factors That Affect Blood Pressure . What
ID: 3509542 • Letter: C
Question
Cardiovascular System, Blood Vessels: Factors That Affect Blood Pressure . What are the three main factors that influence total peripheral resistance (TPRI b. 2. Name three hormones that act as vasoconstrictors b. 3. Name two hormones that directly increase blood volume 4. Thack the effect on blood pressure by reducing venous return. Go through all the steps 5. Categorize the following intor A. Factors that increase blood pressure B. Factors that decrease blood pressure arterial diameter -total vessel length - vessel elasticity plasma epinephrine - blood volume plasma angiotensin stroke volume blood viscosity blood volume -plasma ADH vagus nerve stimulation sympathetic stimulationExplanation / Answer
Answers:
1) Factors affecting the Total peripheral resistance are:
a) Blood vessel diameter
b) Length of the blood vessel
c) The viscosity of blood flowing.
explanation: Total peripheral resistance is the resistance offered by the blood vessels to flow of blood. As vessel diameter decreases, more contact is established between the blood and the vessel wall, therefore, which in turn increases the resistance to flow and the blood pressure rises and the opposite occurs when blood flows through vessels of larger diameter. Hence the arterioles which are small branches of arteries offer the largest peripheral resistance due to its small diameter.
Peripheral or vessel resistance is directly proportional to the length of the vessel and viscosity of blood and inversely proportional to the radius of the vessel.
2) Name three hormones acting as vasoconstrictors.
a) Catecholamines like epinephrine.
b) Vasopressin(ADH)
c)Angiotensin II.
Explanation: A) Catecholamines like adrenaline are secreted by the adrenal medulla. They act on the smooth muscles of the vessels, hence have a direct role in maintaining the diameter of the blood vessel. They cause generalized vasoconstriction and increases BP.
B) Vasopressin or the Anti-diuretic hormone, secreted by the posterior lobe of pituitary gland elevates BP by vasoconstriction.
C) Angiotensin II action is through the Renin-angiotensin-aldosterone mechanism which gets activated by a fall in BP or extreme blood loss. The angiotensin II is a very potent vasoconstrictor and causes a rise in BP.
3) Two hormones directly increase blood volume:
a) Aldosterone
b) ADH.
Explanation: Aldosterone gets released on activation of the RAAS mechanism, causing an increased absorption of Na+ and water through this, increases the blood volume and increases the BP.
ADH acts at the collecting tubules and ends of the distal tubules which has a function to reabsorb as much water as possible, increasing the blood volume, increasing the BP.